The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Known systems used to control operations of aluminum processing baths can include electrical circuits closed when a crust breaking tool breaks an aperture through the hardened upper crust formed on the bath and either encounters a layer of alumina, or the molten layer of aluminum below the layer of alumina. The aperture formed through the crust is necessary to permit feeding new alumina material into the bath. When the electrical circuit closes, a signal is created which directs the crust breaking tool to retract from the crust layer. An example of such a system is disclosed in U.S. Pat. No. 6,649,035 to Horstmann et al. A drawback of such systems occurs when crust material forms on the crust breaking tool or corrosive effects of the bath prevent completion of the electrical circuit.
In this situation, the crust breaking tool can remain in the bath for an undesirable length of time which can further damage the crust breaking tool, or render the detection system inoperative, which prevents feeding of the alumina material, or identification of how many feed events have occurred. A further drawback is the crust breaking tool is generally driven by a system using high pressure air. The longer the crust breaking tool is suspended, the greater volume of high pressure air is required, which increases operating costs of the system and may increase the number of air compressors and air dryers required for operation.